Exercise of Reflection of LightMultiple Choice Questions

Level 1

1.

The figure above shows a large advertising board at night. Which of the following figures best shows how

we can see the boards?

A.advertising board

observer

B.advertising board

observer

C.advertising board

observer

D.advertising board

observer

2.

Statement 1: Non-luminous objects cannot emit their own light.

Statement 2: We cannot see non-luminous objects.

A. Both statements 1 and 2 are correct and statement 2 is a correct explanation for statement 1.

B. Both statements 1 and 2 are correct but statement 2 is not a correct explanation for statement 1.

C. Statement 1 is correct and statement 2 is incorrect.

D. Statement 1 is incorrect and statement 2 is correct.

3.

30

sunlight reflector

The figure above shows a sunlight reflector installed on the roof of a building. At the instant shown, sunlight

falls at an angle of 30° to the horizontal and is then reflected vertically into the building. What is the angle

between the reflector and the horizontal?

A. 30°

B. 45°

C. 60°

D. 75°

4.

Which of the following statements about diffuse reflection are correct?

(1) Diffuse reflection does not obey the laws of reflection.

(2) A clear image would not be formed on a rough surface where diffuse reflection takes place.

(3) We can see non-luminous objects due to diffuse reflection.

A. (1) and (2) only

B. (1) and (3) only

C. (2) and (3) only

D. (1), (2) and (3)

5.

O

plane mirror

P

Q

R

S

A point object O is placed in front of a plane mirror as shown. Which ray is a reflected ray coming from the

object?

A. P

B. Q

C. R

D. S

6.

Peter is standing 4 m in front of a plane mirror as shown. A lamp is located midway between Peter and the

mirror. If Peter wants to take a clear photograph of the image of the lamp, at what distance should he focus?

A. 2 m

B. 4 m

C. 6 m

D. 8 m

7.

A baby is crawling towards a plane mirror at a velocity of 0.1 m s−1. What is the velocity of his image?

A. −0.2 m s−1

B. −0.1 m s−1

C. 0.1 m s−1

D. 0.2 m s−1

8.

A plane mirror moves towards a boy at a velocity of 2 cm s−1. What is the velocity of his image?

A. −4 cm s−1

B. −2 cm s−1

C. 2 cm s−1

D. 4 cm s−1

9.

The image formed by a plane mirror is said to be virtual because

A. it is laterally inverted.

B. it cannot be caught by a screen.

C. it is the same size as the object.

D. it cannot be seen.

10.

A boy of height 1.5 m stands in front of a plane mirror. In order for the boy to see his entire body, what is the

minimum length of the plane mirror?

A. 0.5 m

B. 0.75 m

C. 1.5 m

D. Cannot be determined unless the distance between the boy and the mirror is given

11.

observer

object

P

An object is placed near one end of a periscope as shown. Which of the following figures best represents the

image observed?

A. B. C. D.

12.

observer

object

P

An object is placed near one end of a periscope as shown. Which of the following figures best represents the

image observed?

A. B. C. D.

13.

A boy standing 2 m in front of a vertical plane mirror looks at the image of a picture 50 cm behind him as

shown. What is the distance between the boy and the image of the picture?

A. 2 m

B. 2.5 m

C. 4 m

D. 4.5 m

14.

Which of the following diagrams correctly shows the formation of image by the plane mirror?

A. B.

C. D.

15.

A ray of light falls on a horizontal plane mirror as shown.

In order to reflect the light ray vertically upwards, the plane mirror should be rotated by

A. 10B. 20C. 25D. 50Answer: C

Level 2

1.

In a room ABCD, a tall plane mirror of width 1 m is placed at the middle of the wall BD. The top view of the

room is shown below.

A student facing the mirror wants to see the objects placed at corners A and C at the same time. At most how

far can he stand away from the mirror?

A. 2.25 m

B. 3 m

C. 5 m

D. 6 m

2.

A girl is standing in front of a plane mirror which is hanging on the wall as shown in the figure. She is just

able to see her feet through the mirror. In which of the following situations can she still see her feet through

the mirror?

(1) The girl stands at the same position but raises the mirror.

(2) The girl walks towards the mirror.

(3) The girl walks away from the mirror.

A. (1) only

B. (3) only

C. (1) and (2) only

D. (2) and (3) only

3.

Two light ray emitted by a light source are reflected by two plane mirrors M1 and M2 as shown above. What

is the angle between the two rays reflected by M2?

A. 10B. 20C. 30D. 40

Structured Questions

Level 1

1.

40

incident laser beam

sensor

liquid surface

A student proposes a liquid level indicator as shown above. When a beam of laser is directed towards the

liquid surface, part of it is reflected towards the sensor.

(a) Find the angle of incidence at the instant shown.

(1 mark)

(b) Briefly describe how the indicator works.

(2 marks)

2.

(a) State the laws of reflection.

(2 marks)

(b) A light ray strikes a plane mirror at an angle of incidence of 52°.

(i) What is the angle between the incident ray and the reflected ray?

(1 mark)

(ii) Sketch a ray diagram to illustrate your answer in (i).

(2 marks)

3.

plane mirror

object

(a) In the figure, sketch the image of the object formed by the plane mirror.

(1 mark)

(b) State three properties of the image.

(3 marks)

4.

A boy 1.3 m tall stands 3 m in front of a plane mirror. His eyes are 1.2 m above the ground.

(a) Draw a ray diagram to show how the boy sees himself in the mirror.

(2 marks)

(b) Find the minimum length of the mirror for the boy to see his entire body.

(2 marks)

5.

wall

1 m3 m

boy

plane mirror

1 m

A boy stands 1 m in front of a plane mirror and just observes the image of a wall which is behind him. The

mirror has a length of 0.8 m and it is 1 m above the ground. The distance between the mirror and the wall is

3 m.

(a) Find the height of the wall.

(2 marks)

(b) The boy now stands 2 m in front of the mirror. Would he see the entire image of the wall? Explain your

answer briefly.

(2 marks)

6.

observer

object

0.5 m

0.75 m

0.25 m

An observer looks at an object through a periscope as shown. The distance between the mirrors is 0.75 m.

The object is 0.5 m away from the upper mirror while the observer’s eye is 0.25 m away from the lower

mirror.

(a) State the nature of the image seen by the observer.

(3 marks)

(b) What is the distance between the image formed by the lower mirror and the eye of the observer?

(2 marks)

7.

A ray of light strikes a mirror as shown.

(a) (i) What is the line PQ?

(1 mark)

(ii) Find the angle of incidence and the angle of reflection.

(2 marks)

(b) Complete the following graph to show how the angle of reflection varies with the angle of incidence.

(2 marks)

8.

The figure below shows two plane mirrors M1 and M2 that are perpendicular to each other. A ray of light

strikes M1 with an angle of incidence of 60.

(a) Complete the path of the light ray.

(1 mark)

(b) Find the angle of reflection of the light ray reflected by M2.

(2 marks)

9.

(a) An object is placed in front of a plane mirror as shown in the figure above. Copy the figure into a piece

of graph paper, draw the reflected rays and mark the position of the image.

(2 marks)

(b) State three properties of the image formed.

(3 marks)

10.

E

F

H

T

R0.5 m

plane mirror

A man, represented by the arrow HF stands 0.5 m in front of a large plane mirror as shown. The man is 1.8

m tall and his eyes are 1.7 m above the ground. A tree, represented by arrow TR has a height of 2.5 m. It is

2.5 m behind the man.

(a) Find the distance between the man and the image of the tree.

(2 marks)

(b) Draw, on the figure above, to show how the man sees the image of the tree.

(2 marks)

(c) Find the minimum length of the mirror for the man to see the entire tree.

(1 mark)

(d) If the man stands 2 m in front of the mirror, what would be the answer in (c)?

(2 marks)

Level 2

1.

Jerry Tom

plane mirror

board

1 m

4 m

0.5 m6 m

A B

Two boys, Jerry and Tom, are playing hide-and-seek. At the instant shown, Tom is hiding behind an opaque

board such that Jerry cannot see him in the mirror.

(a) In which direction, A or B, should Jerry move if he wants to see Tom in the mirror?

(1 mark)

(b) What is the minimum distance that Jerry has to travel?

(2 marks)

2.

In each of the following cases, how would you arrange a pair of plane mirrors inside the box to produce the

result as shown?

(a)

(1 mark)

(b)

(1 mark)

3.

An object AB is placed in front of a plane mirror as shown.

(a) (i) Draw the reflected rays and hence locate the position of the image.

(2 marks)

(ii) State the nature of the image.

(3 marks)

(iii) Find the magnification of the image.

(2 marks)

(b) The figure below shows an object placed in front of a periscope. Complete the paths of the two light

rays and hence locate the images formed by the two mirrors.

(2 marks)

4.

A beam of light is directed to a vertical plane mirror as shown in figure (a).

(a) Find the angle of incidence and angle of reflection. Draw and label the normal, the reflected ray, the

angle of incidence and the angle of reflection on the figure.

(4 marks)

(b) Without altering the direction of the beam, the mirror is rotated through an angle in a clockwise

direction (where is smaller than 60) as shown in figure (b). Find the new angle of reflection in terms

of .

(2 marks)

(c) Using the original position of the mirror as a reference line, find the angle rotated by the reflected ray

after the rotation of the mirror in part (b).

(3 marks)

5.

(a) Distinguish between regular reflection and diffuse reflection. You may illustrate your answer with the

aid of diagrams.

(4 marks)

(b) A book printed with glossy paper.is placed under a desk lamp. Glare may appear on the paper and this

makes reader uncomfortable.

(i) Briefly explain why a glare is seen.

(1 mark)

(ii) Suggest possible ways to avoid the glare.

(1 mark)

(c) The figures below show a reading aid that helps us to read in the dark. It illuminates the print from the

side and does not produce any glare, even on glossy paper. Briefly explain why.

(3 marks)

acrylic screen book

light source

6.

object

plane mirror

An object is placed in front of a plane mirror as shown.

(a) Draw the reflected rays on the figure and mark the position of the image.

(2 marks)

(b) State three properties of the image.

(3 marks)

(c) A simple periscope consists of two plane mirrors.

(i) Draw a diagram to show how a person can view an object through a periscope.

(2 marks)

(ii) How does the image formed differ from that formed by a single plane mirror?

(1 mark)

(iii) State one application of periscope.

(1 mark)